The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Motorized vehicles may include a powertrain including a powerplant, a multispeed transmission, and a differential or final drive train. The powerplant produces drive torque that is transmitted through one of various gear ratios of the transmission to the final drive train to drive wheels of the vehicle. Hybrid powerplants may include a combination of an internal combustion engine and one or more electric motors that supply drive torque to the transmission.
Catalytic converters may be used to reduce the concentration of emissions contained in the exhaust gases produced during combustion by the engine that is exhausted by the vehicle. In order to function properly and reduce the concentration of emissions, catalytic converters should be operated at sufficient operating temperatures. The operating temperature of the catalytic converter is largely influenced by the thermal energy of the exhaust entering the catalytic converter. The operating temperature of the catalytic converter is also dependent on the amount of time the engine has been operating.
After prolonged periods of engine inactivity, the temperature of the catalytic converter may be low. During subsequent cold starting, operation of the engine may be regulated during a catalyst light-off process to produce sufficient thermal energy in the exhaust to heat the converter to within a target temperature operating range.
Cold start emission (CSED) diagnostics may monitor a difference between an actual and a desired thermal energy of the exhaust. The CSED diagnostics may monitor the difference, typically referred to as a thermal energy residual, to assess whether the catalytic converter is operating within the target temperature operating range within a desired amount of time. The CSED diagnostics may periodically compare the thermal energy residual with a predetermined energy range to assess whether the exhaust is heating the catalytic converter as desired. Additionally, the CSED diagnostics may monitor the thermal energy residual to assess whether the concentration of emissions meets applicable state and federal standards.